Cam actuated valve mechanism for fluid pressure engines



April 27, 1948. T. c. GRAY I 2,440,259

CAM ACTUATED VALVE MECHANISM FOR FLUID PRESSURE ENGINES Filed March 9, 194 5 14 Sheets- Sheet 1 34 Q?) 3| 6?)- FIG. I

a t/0mm THOMAS c. GRAY April 27, 1948. T. c. GRAY 2,440,259

CAM ACTUATED VALVE MECHANISM FOR FLUID PRESSURE ENGINES Filed March 9, 1945 14 Sheets-Sheet 2 THOMAS c GRAY Q WL April 27, 1948. TQGRAY 2,440,259

CAM ACTUATED VALVE MECHANISM FOR FLUID PRESSURE ENGINES Filed March 9, 1945 l4 Sheets-Sheet 4 @WFW April 27, 1948. 1 AY 2,440,259

CAM ACTUATED VALVE MECHANISM FOR FLUID PRESSURE ENGINES Filed March 9, 1945 14 Sheets-Sheet 5 FIG 8 gill Um T. C. GRAY April 27, 1948.

CAM ACTUATED VALVE MECHANISM FOR ,FLUID PRESSURE ENGINES Filed March 9, 1945 14 Sheets-Sheet 6 m at 3mm E02 0: CI Gray.

mm mm wm N0 mm :ILL

T. C. GRAY April 27, 1948.

CAM ACTUATED VALVE MECHANISM FOR FLUID PRESSURE ENGINES Filed March 9, 1945 14 Sheets-Sheet 7 Own mum 0m 09 mm CNN 0 m v Om mwkzmo ZOE-O2 THOMAS c. GRAY April 948. T. c. GRAY 2,440,259 v THOMAS C. GRAY MAIN CRANK ANGL DEGREES) FIG.|4 W ELM- W April 27, 1948. T. c. aim 2,440,259

CAM ACTUATED VALVE MECHANISM FOR FLUID PRESSURE ENGINE$ Filed March 9,1945 14 Sheets-Sheet 9 INLET PORT OPENING AREA .INS)

THOMAS C. GRAY O! /3 m m 9 m o (D B/ 6 E A) .T o A no X B A {3 v 2 m A. 2 2 i'kk i m O a 8 B In ggwumvfw April 27, 1948. T. c. GRAY 2,440,259

CAM ACTUATED VALVE MECHANISM FOR FLUID PRESSURE ENGINES V IOO o Filed March 9, 1945 14 Sheets-Sheet 10 $2 Q LL 9 1 d 4 fl ro o A w a: (D 0 LL] 3 v N 6 g 3 v I/ 8 g 8 Q E m o mew 0 38 Z N Z O 5/ o m q- 0.

LL I l l m 0 D g O O o O 0.

l.l.| r0 2' m O n o m '0 to m I O glwuc/wkw PORT OPENING AREA THOMAS C-GRAY MW A ril 27, 1948.

CAM ACTUATED VALVE MECHANISM FOR FLUID PRESSURE ENGINES T. C. GRAY Filed March 9, 1945 FIG. l9

14 Sheets-Sheet ll THOMAS C.GRAY\Y moazdmxw 5252 CAM ACTUATED VALVEMECHANISM FOR FLUID PRESSURE ENGINES T. c. GRAY April 27, 1948.

Filed March 9, 1945 14 Sheets-Sheet '12 EXHAUST PORT OPENING AREA(SQ.INS.)

v THOMAS c. GRAY QWL.

April 27, 1948. C, Y 2,440,259

CAM ACTUATED VALVE MECHANISM FOR FLUID PRES SURE ENGINES Filed March 9, 1945 14 Sheets-Sheet l5 M m @E P5552 mm $589 593 x256 25 5250 mzbjmm MC 9% 9% mm 0% v 0% mm: ow. o2 oi n m Km \\W N E u M o H T own 3 mi v\ zoimmmmzmu mmm E 0mm 09 w @5053 wmOJ M A mmm mm: C Qvm 09 mm! mvm April 27, 1948.

r 'r. c. GRAY CAM ACTUATED VALVE MECHANISM FOR FLUID PRESSURE ENGINES Filed March 9, 1945 IOI IOI

l4 Sheets-Sheet l4 FIGY24 THOMAS c. GRAY QW W Patented Apr. 27, 1948 omrsn stares CAM ACTUMTED VALVE MiicnmisM-roa: FLUID PRESSURE ENGINES riiemae c any, United States Navy: Application Marchil, 1945, Serial1-No. 5815 18;

14 claiiiisz (Granted. under the act of March 1883 as amended April 30,

This inventionrelates t'ofluid engines andmore particularlyto new and improved variable 'ev'ent' valve actuatine meenanism therefor;

Iii-ordertomeet the everncreasing: demands imposed upon steam ngines-m1 the matter. of speed; load increasing tnemar efficiency, mcrea'sed" cylinder e'fiicie'ricy (economyand power) and thej like-ther navebeen pronosdnumerous fluid" distributionvalve coii'trblmechanisms whereby the opening arid-closing events of the valve operation could be varied. Itiswellknown' in the artthat there exists forea'ch'engine operating condition" o'f-speed and load. a preferred timedvalve' cycle which'perrnits the achievement I of the-maximumin periormanceor economy for the particular task at hand.-

It is recognized that there have been proposedvarious means wherebyvalve eventscould be varied within certain limits; however; such constructions'have inherent limitations in operation, construction and design which keep them from achieving practical efficiency andcontrol.

The present invention contemplatesthe provisionof improved valve actuating means which Will permit a'variable and selective period between the opening and closing events of the" steam admission and'of the' exhaust valves-and yetretains-a' full and prompt tappet lift action which greatly increases'theoverall efiiciency of the'engine; A1s0,'th"e1engine operator can select the proper admissioriahdexhaust valve events to obtain" the desirerii optimum performance characteristics;

I'nthecycle ofoperation of a steam engine, the inlet valveinormally opens shortly before the point is desirably kept constant at approximately 94% oi the piston stroke. Steam is then exhaiisted through the exhaustvalve' on the return strokes]? "the piston untilthat valve closes and thecomp'ression portion of the stroke begins at the." so-call'ed p'bint of" compression which may vary as required from about 8"t'o2 l% of the piston return-stroke, dependingon engine speed." There'aiterithe sequential cycle of'admission; cutoff: releaseand compression is repeated throughout engine operation? It is obviously desirable that the valves open and close as;nearly instant aneous1y asris kinetica-lly possible-whereby ,fluid flow resistance and wiredrawingt may: be? minimized and; the work or indicator; diagram-areas, may be, kept" ata l maximum;

At low speeds and during. engine starting-operations long-outwit periodsnre requiredvin orderto assure the necessary high starting torque, while."

athigher-speeds the cut-off; period; maybe rshort= le sened" and eqonemy gained by utilizing the -ex'- pansive qualities of the steam.

Desirably; admissionfa-nd '1 cut-oft are controlled by one. inlet valve- -and -re1ease andrcompressionby one exhaust valve both at one end of the cyllsijinclera These valves areduplicated-at the-opposite encrcf the cylinder ofea-double acting steam engine and the valve operation at opposite ends of the cylinder areeangularly timed approximately 180 make advance inr steam engine design essential.

The recently; developed steam -turbine locomotive isrepresentative of an engine? capable of utilizing its boiler potential; 'at all-speeds. Water rates on" z a thi new engine 4 appear-high: atrlow l speeds with rates are-wean satisfactory; as speed is;-increased. Existing steam-fiowl cylinder power/boiler poten;

tial ratios for reciprocating.- steam engines-willijhave to be amply revised-iifthey; are to compete with the Diesel; 1 steam turbine; and the new gas An important requisite -is -thatsteam-- turbine. 7 distribution port-iareas-t -mustbe-proportioned so as'to obtain a-more worthwhile; percentage :of r1potential boiler power at the cylinders=for speeds It-isamobj-ect of the-present invention to-provide -a means for-materially increasing" the efficiency of e'reciprocating 'steam engines;

It*- is= another object of, the present inventien' to provide a practical-means of-'obta-ining controlled steam event cycles and insuring-maximumthermodynamic efiicieney and: greatly improved 5 performance in--fiuid expansion engines.

means wherebyrmaximum valve lift andconse-' quentiy maximum steam flow may be assured-in a variable outwit? fluid, expansion: engine all settings of cut-01hadjustment 'andavailablerpo- 'itenti-ai steam power'mays be utilized:

Still another object of the present invention is" to provide-1a 'sir'nple valve geanmechanism "which is accessible and: isof P the-"package orf unit 1'89- placementrtype whereby, iii-servicing, thesvariable I Wa ve" cbntrl 'mechanis'nrmay b'odily be removed Recent requirements in the line of motive power Another objectzis to-providenew andimproved by inexperienced personnel and may be easily replaced with a standby unit whereby the period during which the engine is idle for servicing may be reduced to a minimum.

An additional object of the present invention is to provide a control mechanism for fluid expansion engines which is easy to adjust and inspect and embodying adjustable remote controls which permit micromatic adjustment of engine cut-off and valve opening events during engine operation.

Other objects and advantages will be apparent from further consideration of the specification and appended drawings in which:

Fig. 1 is a schematic side elevation partially broken away of a steam locomotive embodying the control box of the present invention;

Fig. 2 is an enlarged detailed side elevation partially broken away of a portion of the embodiment illustrated in Fig. 1;

Fig. 3 is a top plan view of the control box and associated valves illustrated in Fig. 2;

Fig. 4 is an interior plan view taken on a line substantially corresponding tolines 4-4 of Figs. 2 and 8, showing the adjustable valve event control mechanism within the control box;

Fig. 5 is a transverse cross-sectional view taken along a line substantially corresponding to line 55 of Fig. 4;

Fig. 6 is a view similar to Fig. 5 taken along a line substantially corresponding to line 6-6 of Figs. 4 and 8;

Fig. 7 is a view similar to Fig. 5 taken along a line substantially corresponding to line '!--'I of Fig. 4;

Fig. 8 is a vertical sectional view taken along a line substantially corresponding to line 8-8 of Fig. 4; 1 1

Fig. 9 is a side elevation similar to Fig. 8 taken along a line substantially corresponding to line 9--9 of Fig. 4;

Fig. 10 is a schematic drawing of the valve actuating mechanism of the present invention;

Fig. 11 is an end elevation taken along a line substantially corresponding to line ll-ll of Fig. 10 and showing the relative location of the cams on the shaft with the engine on dead center;

Fig. 12 is a transverse sectional view of the exhaust cam taken along a line substantially corresponding to line I 2-42 of Fig. 8;

Fig. 13 is a transverse sectional view of the inlet cam taken along a line substantially corresponding to line |3--l3 of Fig. 8;

Fig. 14 is a graph showing the relative inlet cam angular movement plotted against the main crank rotation;

Fig. 15 is a graph showing the inlet port opening area plotted against the main crank rotation;

Fig. 16 is a graph similar to the graph shown in Fig. 15 showing the inlet port opening area' in relation to the area obtainable with a piston i type valve operated by a conventional radial type valve actuating gear;

. Fig. 1'7 is a sequential series of changed position views taken in increments illustrating the inlet cam lobe positions through one piston stroke, when the cam is being accelerated or is leading;

Fig. 18 is a series of views similar to Fig. 1'7, but showing the inlet cam lobe positions when no acceleration or deceleration is imposed upon the cam;

Fig. 19 is a series of views similar to Fig. 17 showing the inlet cam lobe positions when the cam is being decelerated or is trailing;

.4 opening area obtained with the present invention compared with the area obtainedby use of a prior art mechanism;

Fig. 21 is a graph showing the relative exhaust cam angular movement plotted against main crank rotation;

Fig. 22 is a sequential series of changed position views taken in 20 increments illustrating the exhaust cam lobe positions through one piston stroke when the cam is being accelerated or is leading;

Fig. 23 is a view similar to Fig. 22 showing the exhaust cam lobe positions when no acceleration or deceleration is imposed upon the cam;

Fig. 24 is a view similar to Fig. 22 showing the exhaust cam lobe positions when the cam is being decelerated or is trailing.

Principle of operation The valve gear constructed in accordance with the present invention and illustrated in the embodiment herein shown employs rotary cams which engage valve tappets and thereby may operate poppet type valves for regulating the steam admission to, and exhaust from a steam engine of the reciprocating type. It will be obvious that the degree of valve lift and consequently the control of the steam inlet and exhaust cycle is a function of the fixed cam contour which is a physical limitation built into the cam and cannot be modified during use.

Heretofore the limitations imposed by fixed cam contours have been appreciated and various attempts have been made to overcome the bounds of such limitations by many diverse mechanisms whereby the cam rotates in its usual sense and a variable cam eifect is obtained. Some of the proposed mechanisms of the above indicated character are as follows:

Variable profile cam drioes.This type of drive .requires a point contact between a cam roller design and operational problems.

a connecting beam type tappet member.

Two cam parallel shaft drives.--This type of drive employs two parallel cam shaitshaving the same rotation acting upon the opposite ends of With this arrangement port opening is sacrificed as the sired steam distribution nor is it possible to obtain dynamic valve action or near required valve openings. In addition, inherent angularities of motion greatly influence the design and operation.

It is obviously very desirable that the opening and the closure of the steam distributing valves bev as near instantaneous as is physically and kinetically possible; that inlet and exhaust passages be such that fiuid flow resistance and wiredrawing are minimized and that work or indicator diagram areas be kept at a maximum. For economical performance, it is mandatory that the engine utilize the maximum expansive phenomenon of the steam, thus requiring early cutoii and Fig. 20. is a graph showing the exhaust port we release. Steam engine power output varies directly with. the cylinder meanxefieotille pressure and rotational speed. With. lowispeeds and at. startin lon cutoiis "are. required to assure the necessary high torques. while at higher-speeds the clitoris may be shortened andcadvantage taken of the expansive qualities Off'thG steam. Brief y, he events should be desirably controllal approximately as follows:

Admission.-Variablei-.with zero at starting to a maximum. at high speed.

2. CutOlT-.-Varying widely: and decreasing from about 75% to. about 1.0%.,01" the: piston stroke. as they speed oiithe engine. isiin creased.

3. Releosa-nesirably constant at approxn mately the end of the piston stroke.

4. compress-ione-e-llarying from approximately 8% at starting toahoutfid %.of.thc.p.iston stroke at high speed.

The. conventional radial type valve gears. uti-' lize one sin le valve .for the control ofall. four events at both ends of thesame zcylinderwith consequent sacrifices in: power and economyzdue to the unavoidable distortionof valve eventssin the shorter cutoii range. These single. valves are of the well known slidevalve typezused on earlier steam engines, and of the piston. valve type found on a. great maiorityef laterandpres- 811i 5 n ines. Thesemechanisms and valves are greatly handicappedv byhaving to control all events with one valve, with the result that; many events are misplaced and the'available port opens ing areas are f r irom. desired, especially when the shorter cutofis aroused. For-.example,"when the conventionalsteam locomotive valve gear-is adjusted to allow a .0% cutoffiithe. steam is released at near mid-piston stroke-instead of near the end of th workin stroke. obviously, an ppreciable amount oi the. potential useful work is wasted in the exhaust. Also, port openingareas at the shorter cutoffs are such that it is impossible to utilize-a substantial portion of the boiler potential. Attention is directed to the early drooping in the powerespeed curveslof the conventional steam reciprocating locomotive around 55-60 M. P. ilierefiecting the in ability of the engine cylinders -.o utilize the available steam. With the conventionalsystems,port openings are in effect decreased: proportionately s p n sp a ncr ased. When drop ing from approximately 50% cutoff to 2.5% cutofi, the effect on the steam flow-Leas. if the portopenings have been approximately helvedwith conventional valve gears. lhe valve gear ofthe present invention will allow full port opening area irrespective of cutolf selection.

In the present invention in order to achieve a variable valve control it is not-proposed to. modify the cam contour nor to employ a variable movement transmittin mechanism betweenthe cam contour and the valve to be operated but, instead, there is addedto the usual uniform-rotary motion of the valve actuating cam; an. oscillatory cycle of acceleration and. deceleration operating in timed sequence with the uniform circular mo;- tion of the cam drive whereby during-certain portions f h period of ontactxof certain lobes. with the valve tappet thocams maybe. either l y d o a eler t din th ir rotarynaction as desired so as to ac ele a e or deceleratel the-open ing and closing of thevalve.

Th present invention further employs means. c p in a shaft uniformly rotating saidcam ut ad pt d fo re iprocation. whereby through suitable splines the uniformrotary motion may be changed to a nonuniform rotating motion in 6 accordance with empirically predetermined va ve events.

This: invention also pro id s drive means. for

said rotary mot onand said. r ciprocat rys aft movement: which. are interconn ted y an adjustableor variable link arran ement. to pe mit alteration during operation. of the. timed; valve event sequence as. above setforth.

Construction Reierring to the drawings in detail, the present inventionis shownapplied to a steam reciprocating locomotive where it serves to control the sequence of steam inletv and exhaust to and from the. drive cylinders thereof. However, it. will be apparent-that this invention may as readily be applied to any other steam or fluid operated me han sm where im m con ol or fluid o is desired. As shown, the control box comprises a valve operating unit 3!] which may be mounted upon the top of amain cylinder 31 between. the forward steam chest 32. and the after steam chest 33. The operating mechanism within the control box may be driven by any suitable means as by a drive chain 34. operated in timed relation to the movement of the steam piston through suitable connection to .one of the locomotive. axles 35.

In order to provide the desired control, an event control rod 36 extends from the valve control unit to a suitable operating means which may be located inthe cab of the locomotive.

As shown in Fig. 2, the unit 30 may comprise uppeland lower halves secured together at their marginal portions and having an event control connection 38 to which event control rod 35 is secured, and a reverse connection 39 to which the reverse control rod 3'! is secured for operation. These controls may be of anydesired character adapted to operate at a considerabl distance asis well known in the art.

If desired, extensions 40 from each of the control rodsfifi and 31 may pass to the opposite side of; thelooomotive and be so arranged asto also control a similar unit on the opposite side of the locomotive. Any desired linkage may be used for this purpose. Separate linkages may be provided to the locomotive. cab if desired.

-With the unit 30 mounted on top of the main cylinder within which a piston 4i reciprocates, the unitis so dispo ed that outwardly extending inlet valve tappets 42 and 43 will register in axial alignmentwith inlet valves M and 45. As shown particularly in Fig. 3, exhaust valves 45 and 41' may be disposed behind the inlet valves, and the control box 39 operates both the inlet and the exhaust valves for both ends of the double acting steam cylinder. Exhaust valves 46 and 41 are operated by means of exhausttap-pets 48 and 49.

Fig. 3 also shows the drive mechanism which may includea drive chain 34- driving shaft 50 extending into the control box 36. An extension of the. shaft 59 through a suitable coupling 5! reaches to th cylinder on the opposite side of the locomotive, to drive'another valve operating unit identical with unit 311.

Referring to. the disclosure of Figs. 4 to 8 inc1usive,-Fig. 4 shows the interiorof the control box 30 asit appears when viewed along a line substantially corresponding to line 4-4 of Fig. 3 wherein thedrive shaft 58 is shown connected toand directly rotating a drive gear 52 as bymeans. of hub extension 53 thereon. Gear 52 meshes with and drives a smallercrank gear54' which may be journalled on a stub'shaft '55 extending inwardly from the control box wa l and 7 has a crank rod 56 driven [by an inwardly extending crank pin 51 thereon. Rotation of drive shaft 50 and drive gear 52 therefor rotates the small crank gear 54 and reciprocates crank rod 56.

The far end of crank rod 56 is connected to the offset lower end of an arcuate link 58. This arouate link 58 is journalled centrally upon a suitable link trunnion 59 so that reciprocating movement of the crank rod 56 causes the arcuate link 58 to oscillate about its center 59. As shown, a 2 -to1 gear ratio exists between drive gear 52 and crank gear 54 so that for each revolution of gear 52 the arcuate link 58 is oscillated, to and fro twice.

The arcuate slot 68 in the link 56 may receive a link block 61 which is slideably adjustable along the slot. To this link block is secured a radius rod 62 which may be supported intermediate its ends by a hanger arm 64 and the opposite end of the radius rod is journaled to an axially reciprocable cam sleeve 63.

In order to change the amount of axial reciprocation of the cam sleeve 63 for each revolution of drive gear 52, the link block 6| may be adjusted up and down in the arcuate slot 68 to positions above or below its center of oscillation. It will readily be apparent that the length of stroke of the radius rod 62 will increase as the link block moves farther away from the center of oscillation.

In order to raise and lower the radius rod 62, spaced hanger arms 64 and 65 are provided and depend from a hanger arm support 66. The latter has a sector portion 61 disposed adjacent its bearing 68 and the arms may be adjusted by means of a self-locking worm gear 69 which engages the sector 61 and may be operated by event control shaft 38. It is apparent that rotation of the shaft 38 raises and lowers radius rod 62 with a consequent change in the axial reciprocatory motion imparted to cam sleeve 63.

The cams for operating the valve tappets may be mounted on the cam sleeve 63 in the manner best shown in Fig. 8 wherein an inlet cam 15 and an exhaust cam 16 are mounted between cam sleeve journals TI, 18 and 19 which are supported from brackets 80, 8| and 82 extending from the side wall of the control box enclosure. These journals obviously prevent all but rotary movement of the cams. In order to rotate cams l and 16 they may be provided with cam keys 83 and 84 respectively extending into cam slots 83a and 84a of the cam sleeve 63. The keys 63 on the inlet cam '55 register with the slots 83a and the keys 84 on the exhaust cam 16 registering with the slots 84a. This is best illustrated in Figs. 12 and 13 of the drawings.

Cam sleeve 63 may be internally hollow and provided with straight grooves 85 to receive the straight splines 85a on a centrally extending axially movable reverse shaft 86 which is connected to the radius rod fulcrum block 86a. and has a thrust journal 81 at its far end. As shown in Fig. 4, this journal is connected to a movable thrust block 88 which is supported in suitable ways 89 and may be moved back and forth by means of the reverse control rod 31.

The opposite end of reverse shaft 86 is provided with helical splines 96 which engage within corresponding mating helica1 grooves 9| within the bore of the drive gear 52. From the above construction it will be apparent that rotation of drive gear 52 through reverse shaft 86 rotates cam sleeve 63 and the cams th'ereon. Reverse shaft 86 is kept from axial movement by the thrust journal 8'! and maybe adjusted by thrust block 88. The cam sleeve 63 will reciprocate in a manner varying with the location of the link block 6| above or below the center of oscillation of the arcuate link 58. This shaft reciprocates back and forth twice for each rotation of the inlet and exhaust cams.

In order to transmit the motion caused by the cam contours to the valve actuating push rods or tappets, suitable cam follower arms 92, 93, 94 and 95 may be provided which are pivoted at one end to a supporting bracket 96 extending from the control box wall. At the opposite end these arms are provided with tappet engaging bosses 91, which bear against the inner ends of the valve tappets. Cam follower rollers 98 are mounted within an opening in each of these arms and bear against the adjacent cam surface.

Fig. 10 shows schematically the operation of the valve event control mechanism employed in the present invention. As there indicated, rotation of the drive gear 52 which meshes with the crank gear 54 in a two to one gear ratio causes reciprocation of the crank rod 56 and oscillation of the arcuate link 58 about its centrally disposed trunnions 59. In this view the link is shown schematically by a curved line 58a connected to the end of the reciprocating crank rod 56. This line 58a has nine stations numbered at intervals to indicate relative points to which the link block 6i may be adjusted as desired. Of course, the selection and numbering of these stations is merely for the purpose of reference and the link block may be positioned at any desired intermediate position.

Assuming for the moment that the link block BI is in position No. 9 at the lowermost portion of the arcuate slot 60 in the link 58 and startin from the position shown in Fig. 10 with the crank gear 54 rotating clockwise, the crank rod 56 and the lower end of the associated link 58 will be drawn to the right and, by means of radius rod 62 the cam sleeve will be moved to the right through a lobe trailing path 99. Since the inlet and exhaust cams have uniform circular motion at dead center position as defined by the drive gear 52, movement of the cam sleeve 63 to the right with the helical splines of the character shown will obviously cause cam rotational delay and will retard the rotative motion of the cam.

It will be obvious that continued rotation of the crank gear 54 more than of its rotation (90 of the rotation of drive gear 52) will move the crank rod 56 back to the left moving with it the lower end of link58 and the radius rod 62.

This returns the cam sleeve again to its starting I returned to their initial position with respect to the drive gear 52.

By the above arrangement there has been added to the uniform rotary motion of the cams a, non-uniform decelerating and an accelerating movement which occurs in timed relationship to the uniform rotary motion of the cams. It will be evident that at any intermediate station along link 58 such as 8, 7 or 6 a similar phenomena will occur though in less degree.

The non-uniform deceleration and acceleration just described with reference to a trailing action of the cam lobe may be provided in the opposite form by moving the link block 6| to any station above the center of the link 58, such as station 1. With this arrangement rotation of the crank gear 54 clockwise causes movement to the right of the lower part of the crank rod 56 and a correspondsn re- 25a ing movement to the left of the upper portion of the link 58. This draws the radius rod .62 to the left moving the cam sleeve 63 into a lobe leading position I80 so that to the uniform. rotary move= merit of the cams there is imparted an additional non-uniform acceleration during a portion of the rotation of these cams and consequent corresponding deceleration during the remainder'of that rotation.

Figs. 17, 18 and 1!) illustrate the relative rota- I tion of the cam in its acceleration and deceleration through a period of 180 with relation to the uniform rotary motion of the drive gear-:52; In Fig. 17 inlet cam with itsjoharact'eristl'cally short lobe is shown in schematic outline in the changed positions occupied at incrementsduring 180 of crank rotation. The arrow 41 :in each of these figures showsthe norm'ai uniform rotary motion of the drive gear 54. Fig. 17 slfows the inlet cam leading the uniform rotary motion. Fig. 18 shows the inlet cam coinciding with-the uniform rotary motion while Fig. 19' showsthe inlet cam trailing the uniform rotarymotlon.

Figs. 22, 23 and 24 illustrate the exhaust cam in similar changed position form, thou'g-h itw-ill be noted that the magnitude ofthe leading and trailing action is normally less. Y

It will be obvious that the amount and degree of acceleration and deceleration varies and is a function of the angle of the hel-l'ealai-nslotsflu and 84a to which the cams are keyed. Thus-the inlet cam 15 will normally have a helical-spline with a degree of lead considerably inex'cess oi the helical spline which controls the advancing and retarding of the exhaust valveeain l6. wise such grooves instead or being uniform straight line helices may b'e' in theiormotneliees with a gradually increasing ang'leof attaek'so that during certain portions of the mover-neuter the cam sleeve'63 the aniountof earn adva of; or retard may bea'cco'rdin'gl'y' varied; 3 Tunis-arose ter ofdesign.

an additional important feature orthepres" t invention is the provision of accurate n whereby a microm'at'ic adjustmentfofthe degree of cam lead may be achieved; This adji'is'tiii'eiit includes the reverse mechanism comprising re= verse shaft 86 and its operating'partls which-are adjusted by the reverse control roast;

As shown the reverse shaft 86 transmits the uniform rotary drive motion from dr ve-gears: to the axially slidable'rnultiple splindcani sleeve 63. The straight grooves 85 merely sefve to transmit rotary motion from 'the'slia'ft 8G tothe cam sleeve 63 without changih'g theuni-foi'inity of the rotation. However, the helical' spl ines'fio on the far end of the shaft, by engagement within the corresponding and mating helical grooves a 1 inside of the drive gear 52 may; byaxial move ment of the shaft, cause the cahl'sleeve to rotate and to carry with it in its exact rotation; the inlet andexhaust cams. The amountof-rotation of the'reverse shaft 86 is 'a function of thelead angle of the splines and grooves lill'and 91:

It will be iurther'apparent that'theabove iridicated reverse means mayalso be employed to vary thedegree or lead whichisemployed; This isindieated in Fig. 10 whereas shown, a'zero lead may be employed for greatest traetlve efioit iii starting the locomotive and; ass'peedis inoreas'ed, the amount of lead may be increased so as to increase the amount or preadinis sion thereby properly cushioning the inertia. :efiects of the moving parts.

it will be apparent-horn *theabove construction 10 that movement of the reverse control lever from the forward position in 'Fig. 10 to the reverse position will result in asubstantial rotation of the cam slievesand both cams mounted thereon so thatthe cams are in-a position to control reverse motion 'ofthe engine; The amount of movement rcufircd to'accoriiplish-thisis; of course, a function' orthe lead angle of the reverse shaft helices.

'In Figs.-1-2-and13 are shown representative cam cdntours which may be employed in the present invention: As there indicated the exhaust cam W-in ffig. 1-2 has -an-elongated-tappet engaging face 102 while theinlet-cam II is provided with a tappet engaging face -H|3of materially reduced area. Theselect'ed' design ofthe cam iaces will,

oncourse, depend upon a number of variable factors whioh'areto be'considered in the present valve-actuatingmechanism-.-

In Fig-A4 is shown graphically the relative inlet cam movement in terms of cam angle with relationtothecrank ang-le'of the reciprocating steam engine. Thus, in thisview the nine representative positionsa'bove described are laid out and the {amount-cream leador cam lag-incident thereto is illustrated. c

Fig.f15 .is"iilustrated graphically the lihlet pore opening area insqiiare inches per degree of steam engine crankangle janld it will be noted that the area increa'ses radically without an extensive amount nf preadmission lead so that inaximurn steam flow is obtained with resultant increase in power, and a desirable power output/boilerpotential ratio, can be realized.

In Fig. :16 the i-nlet port ope -iing area is illustrated as compared to the conventional inlet: port area v 1; lotte'd againstthe crank angle in degrees. The amount of preadmission'heretofore required and consequent los-s due to unnecessary piston retarding pressu-re' thus obtained i readily apparent: Likewise, irom -thisgrapnit will be seen that? the sport opening --area of the conventional engine varies; with the amount of cut-oif. to which the valve mechanism is set. Thus a-ssumingwthe proposed device provides .an inlet; port opening'area 'of-100%, cut off curve No. -l with the' conventionalengine permits an inlet port opehing area -of approximately 30.0%and requires a preadmission opening point in degrees. of crank angle of approximately 330 while with a valve control unit constructed" in accordance with the present-inventionaeut off curve la at 12% cutoff permitsn 190%openingof theinlet port and the valve need not"start"to openuntil about 343 of craiik anglerotation-z' Similar improved perfrmancPwi-llbe noted by comparing cut-off curves 3 and 3a of the graph.

Fig. 20 is a similar-graphfr the exhaust valve and lt will be noted 'that with the conventional exhaust valve opei'atingmechanism and a cutofi of l2 %"curve-Norl start-sat a point between 75 and'80*ofthemain crank angle and stops at approzilm'ately 290 ofthe main crank angle. Withthe-eontrol mechanism of the present invention;inereasedexpansion may be permitted and g-renter"thermal eificiency obtained by not opening the-exhaust valve in-a 12% cut off curve until:approgimately of=crankangle and the valve ma y tnenelose" at approximately 305 of crank an'g-le: Sifrillafi emeientlperformanoe for other cut-oil positions are indicated upon this raph. r

Fig; "214s: anew ar to Fig; 14" and'shows the-=relative-exhaust ind merit in a valve actuating-cente constructed i accor ance with the'eresent 'ihventios; As in litherelative are numbered upon the chart. 1

Of course, the present; invention is susceptible to modification in many particulars and the proportions indicated are given as merely representative of one embodiment that this invention may assume. To those skilled in the art it will be apparent that the operation of the device may be varied by modifications in the shapes of the inlet and exhaust cam contours, the shapes of the slots in the cam sleeve, the construction and Shape of the link arm and other obvious proportions which may be changed at will to suit the requirements of the engine.

For purposes of illustration the operation of a valve control unit in accordance with the present invention may be shown in the following table, where the figures indicate the per cent of piston stroke where the following events take place:

Preadmission Release Compression Cutofi Gray Piston Gray Piston Gray Piston Per cent Per cent Per cent Per cent Per cent Per cent Per cent 10 2. 85 42. 9 22 42. 9 2. 0 6. 2 89 50. 4 17 35. 8 1.0 4.4 a 91 55.7 14 31.0 l. 0 3. 4 93 60. 3 ll 27. 3 5 2. 1 95 67. 8 9 21. 1 50 4 1. 2 96 76. 8 7 14. 6 60 3 74 97 82. 1 6 l1. 0 70 2 60 98 v 87. l 5 7. 8 80 0 99 91. 6 3 4. 9

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefor to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing illustrative description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. v

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

1. A fluid distribution control unit for actuating the valves of an elastic fluid engine comprising inlet and exhaust valve operating cams, engine driven means for imparting a timed rotary motion to said cams, and adjustable means including an axially movable sleeve for advancing and retarding the rotary motion of the cams during successive portions of their rotation.

2. A fluid distribution control unit for actuating the valves of an elastic fluid engine comprising inlet and exhaust valve operating cams, engine driven means for imparting a timed rotary motion to said cams, and adjustable means including an axially movable sleeve for advancing and retarding the rotary motion of the cams during certain periods of their cycle of rotation, the sleeve being separately connected to the inlet and exhaust valve operating cams by helical splines whereby the relative advancement and retarding of each during portions of the rotary cam cycle is a function of the angle of said helix.

3. In a fluid distribution control unit for actuating the valves of an elastic fluid engine, the combination of individual inlet and exhaust valve operating cams, with means for imparting an irregular rotary motion to the cams comprising a rotatableand axially moveable cam supporting sleeve having independent helical splined .eonnec'= tio'ns for driving each of the cams, drive means for rotating'said sleeve in accordancewith the engine rotation, and means for imparting'a timed axial reciprocation to' the cam supporting sleeve whereby the cams are accelerated and decelerated during timed portions of their rotation.

4. A fluid distribution control unit'for actuating the valves of an elastic fluid engine comprising a sleeve rotatablydriven by said engine, individual inlet and exhaust valve operating cams mounted upon and rotated ,by the sleeve, independent helical splines of dissimilar angles'connecting said cams to saidsleeve for accelerating or retarding the camsintheir rotation by axial movement of the sleeve in timed relation to the rotary movement whereby said cams are accelerated and decelerated with respect to the normal rotary movement of said sleeve.

5. A poppet valve cam motion control mechanism wherein a cam having approaching surfaces and receding surfaces is non-uniformly rotated to decelerate during said approach, hesitate at the peak of, opening for a variable length of time, and accelerate during receding movement of the cam, comprising a cam supporting member, means for rotating said cam supporting member, a cam mounted on said cam supporting member, means for reciprocating said cam supporting member in timed relation to said rotation, and a helical spline and groove connection between the cam and the cam supporting member whereby the rotary motion is communicated directly to the cam and the reciprocating motion is transformed into rotary motion of said cam during timed periods of the cam rotation.

6. A poppet valve cam motion control mechanism wherein a cam having approaching surfaces and receding surfaces is non-uniformly rotated to accelerate during the cam approach, hesitate at the peak of valve opening and decelerate during the cam receding. movement comprising a cam sleeve, means for rotating said cam sleeve, a cam mounted on said cam sleeve, means for reciprocating saidcam sleeve in timed relation to said rotation, and a helical spline and groove connection between the cam and the cam sleeve whereby the rotary motion is communicated directly to the cam andthe reciprocating motion is transformed into rotary motion of said cam during timed periods, of the rotary movement, and reversing means for said control mechanism comprising externally operable means to bodily rotate the cam sleeve andcams thereon through substantially /2 of a complete revolution.

'7. A fluid distribution control unit for actuating the valves of an elastic fluid engine comprising a support, a rotary drive gear mounted on the support and driven in timed relationship with the engine, a cam sleeve rotated by the drive gear, valve operating cams mounted upon the sleeve and secured against other than rotary movement, a helical'splined drive between'the cam sleeve and the cam, and means for reciprocatingsaid sleeve during continued rotary movement thereof in timed relation to its rotation whereby the speed of rotation of the cams is varied in various portions of their rotary movement.

8. A fluid distribution control unit for actuating the valves of an elastic fluid engine comprising a housing, a rotary drive gear mounted within the housing and'driven in timed relationship with the engine. a cam sleeve rotated by the'drive gear, cams mounted upon the cam sleeve and secured 

